Trimmer mechanism for sewing machines



July 7, 1936. E. M. HANF TR IMMER MECHANISM FOR SEWING MACHINES FiledMay 11, 1935 gwuvwbo'b' Edward 1711101 Patented, July 7, 1936 PATENToFFicE.

TRIMMER. MECHANISM" FOR SEWING MACHINE Edward. M. Hanf, Bridgeport,Chum, assignorto Thesin'ger Manufacturing Company, Eliza;- beth', J-.,acorporatioirofNewJersey yApplicatioxi May 11, 193-5, Serial; m mas i '4Claims. .(c1.112 127) Thisinvention relates to trimmer mechanism forsewing. machines. and more particularly to improvements in underedgetrimmer mechanisms designed for trimming off the margin of the under-'5. of twoor HIOIQDHQSgOf material in the operation of uniting saidplies by stitches.

It is the primary object of the present invention to provide'durablemeans for maintaining an effective shearing relationship between themovable and ledger-blades of a trimmer mechanism and more specificallyin the trimmer mechanism disclosed in the U. S. patent to- J. C. Binge,No. 1,526,436, Feb. 17, 1925.

The invention consists in the improved knifebar guiding meanshereinafter described and as set forth in the appended claims.

In the drawing, Fig. 1 is a front end elevation of the bracket-arm headand a portion of the cloth-plate of a sewing machine containing apreferred embodiment of the present invention. Fig. 2 represents asection of the bracket-arm head in a vertical plane adjacent to thetrimmerbar. Fig. 3 represents a perspective view of the trimmer-barguide-stud. Figs. 4 and 5 represent perspective views of the trimmer-barguidebrackets.

The sewing machine, partly illustrated in the drawing and more fullydescribed in said prior Patent No. 1,526,436, has a horizontallydisposed bed-plate I supporting a throat-plate 2, suitably apertured toreceive a feed-wheel 3 and recessed in its upper face to receive aledger-blade 4. Adjacent to the ledger-blade 4, the throatplate isprovided with a vertically inclined trimmer-knife aperture 5.overhanging the bedplate I is a bracket-arm head 6 in which is pivotallyhung a swinging frame 1 providing bearings for a verticallyreciprocatory needlebar 8 carrying at its lower end a needle 9.Journaled for vertical movement in suitable bearings provided in thebracket-arm head 6 is a presserbar ll) carrying at its lower end aroller-presser H yieldingly opposed to the feed-wheel 3.

Vertically slidable in the upper end of the presser-bar I is aspring-pressed trimmer-lifter rod 12 engaging an angular plate l3suitably secured upon the upper end of a trimmer-bar I4. The trimmer-barI4 is journaled within the head 6 for endwise reciprocatory andlaterally vibratory movements resulting in a vertically inclinedoperative path of said bar. For this purpose, one side edge of thetrimmer-bar, adjacent to its upper end, is provided with a roundedproturberance I slidably engaging a wall l6 of a trimmerbar guidingrecess I! in the bracket-arm head 6 Opposedto the recess-wall l6 is aconvexly curved. wall |8- engaged by the-slightly concave edge l9- ofthe trimmer-bar opposite to the protuberance I 5, thereby providing asliding fulcrum for the trimmer-bar whichtis confined by 5 the walls ofthe recess H to movements in a vertical plane transverse to a verticalplane containing the line of feed of the work.

Adjacent to its lower end, the trimmer-bar I4 is provided withsubstantially parallel guides 20, 10 2| constituted by the edges of saidbar which are opposed to each other transversely of the line of seamformation, said guides being inclined to the length of the trimmer-bar.The guide 20 slidably engages a guideway 22 comprising the 15 diametralface of a substantially semi-circular guide-stud head 23 having abearing trunnion 24. The arcuate portion of the segmental head 23 of theguide-stud and the trunnion 24 thereof are journaled in a shoulderedbearing-aperture 20 25 provided in one member 26 of an angularsupporting-bracket, the other member 27 of said bracket being secured byscrews 28 upon the head 6 of the machine bracket-arm. The bracketmember26 is partly cut away to provide a trim- 25 mer-bar confining face 29terminating in a vertically inclined shoulder 30 intersecting theguide-stud bearing aperture 25. The guideway face 22 of the guide-studprojects beyond the bracket-shoulder 33, thereby constituting a rock- 30ing bearing for the trimmer-bar guide 20 independently of said shoulder.

Directly opposite to the guideway 22 of the guide-stud is an adjustablescrew 3| endwise engaging the trimmer-bar guide 2|, said screw 35 3|being adjustably threaded into a bracket 32 secured by screws 33'uponthe head 6 of the machine bracket-arm. It will be understood that byreason of the described guiding means for the trimmer-bar M, the lowerend of the 40 trimmer-bar will be vibrated laterally upon endwisereciprocation of said trimmer-bar. The pivotal guide-stud 23, 24provides for maintaining the entire length of the guideway 22 of saidguide-stud in engagement with the guide 20 of the endwise reciprocatoryand laterally vibratory trimmer-bar l4, thereby insuring accurateguiding of said trimmer-bar.

Adjustably secured by screws 34 to the lower 50 end of the trimmer-barI4 is a knife-holder 35 to which the vertically inclined trimmer-knife36 is suitably secured.

The trimmer-knife has the usual guide-finger 31 adapted to enter thethroat-plate aperture 5, 55

and has a cutting edge 38 which coacts with the ledger-blade 4 to severthe work.

Endwise reciprocatory movements are imparted to the trimmer-bar M by avibratory arm 39, releasably connected to said bar by a stud 40 adaptedto enter a notch 4| in a side edge of the trimmer-bar, said arm 39 beingcarried by a rock-shaft 42 which may be actuated in any usual orsuitable manner.

Having thus set forth the nature of the invention, What I claim hereinis:

1. Trimmer mechanism for sewing machines comprising, a trimmer-knifecarrying bar provided with a guide inclined to the length of said bar,actuating mechanism for endwise reciprocating said bar, a rockingguideway slidably engaged by said guide, and means effective to maintainsaid guide and guideway in sliding engagement.

2. Trimmer mechanism for sewing machines comprising, a trimmer-knifecarrying bar provided with a guide, actuating mechanism for endwisereciprocating said bar, a rocking guidestud slidably engaged by saidguide, and means adjustably opposed to said guide-stud for maintainingsaid guide and guide-stud in sliding engagement.

3. Trimmer mechanism for sewing machines comprising, a, trimmer-knifecarrying bar provided with a guide inclined to the length of said bar,actuating mechanism for endwise reciprocating said bar, a rockingguide-stud having a trunnion and a head providing a guideway slidablyengaged by said trimmer-bar guide, a journal-bearing for the trunnion ofsaid guide-stud, and means effective to maintain said guide and guidewayin sliding engagement.

4. Trimmer mechanism for sewing machines comprising, a trimmer-knifecarrying bar provided with substantially parallel guides, actuatingmechanism for reciprocating said bar, a rocking guide-stud having atrunnion and a segmental head providing a guideway slidably engaged byone of said trimmer-bar guides, a journal-bearing for the head andtrunnion of said guide-stud, and an adjustable screw disposed directlyopposite to said guideway and endwise engaging the other of thetrimmer-bar guides.

EDWARD M. HANF.

